Dehydrating system for the walls of cold-storage rooms



Aug. 14, 1956 c. G. MUNTERS DEHYDRATING SYSTEM FOR THE WALLS OF COLD-STORAGE ROOMS Filed May l. 1951 r ...ik

United States Patent @hice Patented Aug. 14, 1956- DEHYDRATING SYSTEM FR THE WALLS OF COLD-STORAGE ROOMS 'Carl Georg Muuters, Stocksund, Sweden Application May 1, 1951, Serial No. 223,887

3 Claims. (Cl. 34-80) Test pieces taken from the walls of cold-storage rooms which have been in use for some years show that water is collected in the insulation of said walls in quantities such as to increase the coeiicient of heat transfer considerably-up to 100% and more-which involves, among other things, a corresponding increase of the operating costs. Cases are known Where the insulating capacity has been reduced to an extent such that the refrigerating machines can no longer maintain the necessary temperature in the cold-storage rooms. This disadvantage becomes greater, as the temperature of the cold-storage rooms is lowered, for instance to -20 to `30 degrees centigrade and more, in accordance with the requirements of modern cold-storage technique.

To find a remedy for this, it is known to arrange a ventilation passage system in the walls, which is traversed by air with `a low precentage of humidity. As disclosed in my U. S. application Ser. No. 761,682, led July ,17, 1947 (which matured into U. S. Patent No. 2,623,364 on December 30, 1952), said passages are brought into communication with a dehydrator through conduits, including a fan, so that a `dehydrating system, separated from the interior of the room, is obtained. The dehydrator is adjusted to a temperature which is lower than the lowest temperature prevailing in the wall, that is to say, lower than the temperature of the portion of the insulation located adjacent to the cooling chamber. This has been found to be required in order to prevent precipitation of the moisture, independently of where the above-named passages are located in the wall. Thus, if the passages are located near the outside of the wall, Where the temperature approaches that of the atmosphere, it will not be found to be feasible, contrary to previous belief, to cool the air entering the wall by only a few degrees, it being necessary in this case too, to reduce the entrance temperature of the dehydrating air below the lowest wall temperature. Ventilation on the warm side of the Wall therefore involves a considerable loss of energy, by reason of which the passages are preferably to be located on the cold side or, in other words, as near the cooling chamber as possible.

This invention primarily yaims at forming a supplement to the yabove-described dehydrating system to be used, for example, if cooling chambers are supplied with cold by means of air of the desired temperature, which is blown through the same from a source of more or less distantly located cold. It may then occur that there is no cold generating apparatus Iavailable in the proximity to impart to the dehydrating air passing through the dehydrator the requisite subtemperature of, for instance, 6 C. compared with the temperature of the cooling chamber. Another case is where in the winter time the temperature labout the cooling chamber falls below that of the chamber, so that the refrigerating apparatus in the latter is cut off. Moisture in the walls will thus continue to leak in, but in a direction opposed to the former direction, and inasmuch as the refrigerating `apparatus is cut off, a dehydratbeing obtained by the operation of the existing refrigerating apparatus.

The main feature of the invention kis to provide a dehydrating system of the class described in which the dehydrator contains a dry absorption medium with which the dehydran'ng lair is brought into'contact during its circulation in the system, and which is adapted to lower the partial pressure of the water vapor in the said 1air to a value which is lower than the partial pressure of the water vapor at the temperature of the cooling chamber.

A11 absorption medium, such as silica gel, may in its dry state (when the percentage of moisture is about 6 per cent by weight) absorb a percentage of weight of moisture corresponding to the relative humidity of the air flowing therethrough, said percentage of moisture becoming greater proportionately to the approach of the water vapor therein to the state of saturation. If it be assumed that a cooling chamber has a total inner surface of 1000 square meters and that the temperature thereof is to be -20 degrees centigrade, the requisite quantity of air will be about cubic meters per hour on the condition that the walls are constructed in the ordinary manner with two external asphalt coatings. This air gives off 0.4 gram of moisture per cubic meter to the absorber. In regenerating the absorber once every twenty-four hours, the quantity of silica gel becomes 6 kilograms, which is iaccommodated within two layers of 5 x 30 x 30 centimeters, that is to say very ample dimensions if the specific weight is 0.5.

drating air may be taken oif at any point of the wall, since this air is not required to be subjected to any lowering of the temperature. The eflicicncy consequently is just as high whether the passages in the wall are provided on the cold or on the warm side. However, the absorption capacity per unit of weight of the absorption medium will be considerably less in the former case. In the example given above, the pass-ages are provided adjacent to the cooling chamber, but if they are displaced to the outside of the wall, the quantity of absorption medium needed will be about 10 times larger.

The invention will he described more in detail hereinafter wit reference to an embodiment thereof illustrated by way of example in a vertical section on the accompanying drawing, other features distinguishing the invention being also set forth.

In the drawing, 10 designates the supporting structure or frame of a cooling chamber, which structure may be of any type known per se and may form a part of a larger building structure comprising a plurality of cooling chambers. Provided on the inside of this frame on all s'ides of the same is a layer 12 of an insulating material, such as cork or a'multi-layer insulation, said layer being covered toward the inside of the chamber by a layer or covering 14 of plaster or slabs. Arranged between kthe insulating layer 12 and the frame 10 is a coating 16 of a material permitting diffusion of moisture therethrough only with difliculty, such coating consisting primarily of asphalt,

which'is preferably applied in two layers on the inside of 'r An advantage of the absorption medium is that dehy- Y groups of dehydratingY channels withiny the Wall.

as` shown inmy above-mentioned application. Provided along. the corner. linesl 'are headers.4 or. distributing. andcollecting channels 2t) and 2,2, respectively, adapted to provide a uniform distribution of the circulating air, which may! beiintroducedat the. top through an intake 24; at themiddle ofrfthe rightrhand upper corner line in the drawing, and which may escape through aconduit 26extending diagonally opposite the Vair. intake. Arranged over;v each ofthe twol remainingl lateral walls. are similar spaces, to which the Ventilating air is supplied throughconduitsZS: provided indivi-duallyffor each of said clearances, said. air being .permitted to escape through conduitsdonitshaving beendistributedzover. the wall sur-v .face with the.A aid of. similardistributing and. collectingr channelsV 31-andf32, respectively. Arranged outsideY the cooling chamber is a. dehydrator 34;containing a number of; layers.36ofa dry; absorption medium, such as silica gel, there-being two of these layers in theV present instance; Thelayersare kept in position between screens 38. A., conduit 40 opens intolthe intermediate space between thetwo layers 36 and communicates withthe conduit 26fand the two conduits 30, which may have valves 42arranged therein, said valves being adjusted so that a suitablequantity of` air. will passthrough the individual Two conduits 44 extending from the dehydrator34 on the sides of. the silica gel layers 3 6. remote fromc each other are united: into aA conduit 46, which may be in constant open communication with the atmosphere through a conduit 48. The conduit` 46 has. a further channel communication 50 with the. atmosphere, a. valveV 52 being provided to cut oft'leither this communication or the conduit 46. The latter conduit is extended to-the suction side of a fan 54, from which-the circulating-air is conveyed through a conduit.56 to the. above-mentionedintaltes 24 and 28.

AAbranch conduit 58 connects the conduit 56 with the conduit 40. The conduit 58 is connected to a chamber 60 containinga heating serpentine` 62. A valve 64 is adjustableinto two positions, thatisto sayfrom the position shownin the drawing, where-theconduit 58 is disconnected fromthe conduit 40, into a position-where the communication between the. outlets 26 and 30 and thedehydrator 3dA is interrupted. Those portions of the circulation. system outside the cooling chamber through which the dehydrating.- air passes during the ventilation of-thewalls are heat-insulated from the surroundings by meansoflayers of asuitable insulating material asV indicatedzat` 66, so that this air will be influenced as little-as possible by the temperature of the surroundings, said-temperature being considered to be higherthan that prevailingin the channels 18.

Thesystemfunctions in the following manner.

It assumed-that dehydration ofthe walls takes place. The valves 52 and 64 then take the-positions according to theH drawing. The fan 54sucks air through the absorption layers.36 of lthedehydrator so as to become demoistened, and then forces thezair into the channel system of thewalls.r The air on having absorbed moisture from the wall insulation returns to the dehydrator, the valve-or valves 42- ensuring that a quantity of air adapted to be just suilicient will run through the various channel systems. A- low temperature is maintained in the circulation system and thus also in theiparts thereof located outside the lwall, said temperature corresponding to that prevailingin the channels-18, which is thus near the low temperaturefofthe cooling chamber generated by the-refrigerating-- machine thereof, a. matter which, as stated above, inuences the dimensions of the absorbing layer in an advantageousV manner.. quired to adjust the dehydrator to the low temperature.

The dehydrator 34 is regenerated at certain intervals, for instance every day or every other day. To this end, the Valves 52 and 64 are adjusted into their other extreme position, the heater 62 being switched in at the same time, which may be eiiected automatically upon an impulse froma clockorthe-like inamanner known per se. The fan 54 will now'suck in` fresh air throughA the passage 50 and convey this air into the chamber 6i), wherein it is heated to C., for example. The air then continues into the dehydrator and flows past the layers 36, from which the absorbed moisture is expelled, whereupon the air escapes through the-mitlet 4810 the atmosphere. The dehydrator and the absorption medium arranged therein are so devised that the partial pressure of the air passing through the dehydrator will be lower than the saturation pressure ofthewater vapor at the temperature of the cooling chamber, at least during the greater part of the day.

While onemore or less speciiic embodiment of the invention has4 been shown, it is to be understood that this .isfor purpose of, illustration only, and the invention is.

not to be limited thereby, but itsscope is to be determined by the appended claims.

What I claim is:

l. The combination, with a refrigerating room having walls containing insulation formed by` masses of solid:

material intowhich moisture diffuses, of a system for dehydrating the insulation comprising ventilation spaces located: in said walls and in diffusion relation with the insulation therein, conduit means located outside said room andgcommunicating at spaced places with saidspaces toA provide a circuit for circulation of air through said spaces, said conduit means including a fan for eliecting said circulationl and a drying; room containing a solid moisture absorbing agent for removing moisture'from air taken from said spaces-before the return thereof to said. spacesand means'for selectivelyestablishing a circulation.- of air, through said conduit means independently, of saidA ventilation spaces for periodically regeneratingtsaidsolid moisturerabsorhing;agent, said last mentionedmeansincludinga-bypass conduit communicating with said conduitY means on; the Vdischarge side of said fan and on the inlet side-of.y said drying room and heating -rneans disposed in saidbypass,conduit.`

2, Structure-as.denedinjclaim l includingvalve means operableftoprevent circulation ofV air Vthrough said-bypass.

conduit,

3,. Structure asgdetned in claiml including an outlet from saidiconduit-meansl on the discharge side of said..

dryingtroonganinletto said conduit means onlthe-inlet side; c fsaid;fan andvalveY means for controlling said inletandior, controlling ow through said conduit meansoperabletofprl-eventcirculatory flow through said circuit@ and' to permit how. of air from an external sourcethrough said bypassconduit-including-saidheating means and through said-, dryingyroomfromsaid inlet to said outlet.

References Cited inthe file of this patent UNITED STATES PATENTS 1,856,008 WarrenV .Apr. 26, 1932 2,016,608 McDowell et al Oct. 8, 1935 2,441,571 Heineman May 18, 1948' 2,485,630 Munters Oct. 25, 1949 2,563,042 Jaubert Aug.17, 19514 Thus no special cold producer is re 

